Heat exchange system for thermoelectric generators



Jan. 8, 1963 s. POGANSKI ETAL 3,071,932

HEAT EXCHANGE SYSTEM FOR THERMO-ELECTRIC GENERATORS Filed April 12, 1961N I .1 k

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lllllll/l/I/A .7 n v e n10 r5 .S/EGFR/ED POGANSK/ JOHANNES HOFFMAN/VUnited States Patent Ofifice 3,li7l,932 Patented Jan. 8, 1963 3,071,932HEAT EXCHANGE SYETEM FOR THERMG- ELEQTREC GENERATORS SiegfriedPogansioi, Langeu, Hesse, and Johannes Holimanu, Frankfurt am Main,Germany, assignors to Lieentia Patent-Verwaltuugs-G.m.h.H., Frankfurt amMain, Germany Filed Apr. 12, 196i, Ser. No. 1i2,51d Iiaims priority,application Germany Apr. i3, 196% 15 Claims, (Cl. 62-3) The presentinvention relates to a thermo-electric generator; more particularly,this invention relates to an im provement in the heat exchange system ofa thermo-electric generator.

The recent development of suitable materials for the members of athermo-couple, brought about the employment of the Peltier effect as anefficient mode of cooling or heating. The Peltier effect is the knowninverse phenomenon of the generation of an electric current bydifferently heatin" the two soldering spot or junctions between pairs ofdissimilar thermo-electric materials.

For economically using the Peltier effect, it is necessary to providefor a good heat exchange between the effective thermo-couple junctionand a cooling or heat exchange medium. Known devices for example, employtubes on which is mounted one or more thermo-couples, and the heatexchange is carried out through the walls of such tube. This isinherently ineificient because the inevitable strong temperaturegradient in the tube wall reduces the eifective heating or coolingtemperature. According to other solutions, the heat exchanger of thethermo-couple is provided with a bore being passed through by the heatexchange medium. This is also disadvantageous, because a very largeexpenditure is required with regard to sealing material and constructionwork.

It is a primary object of the present invention to provide for a new andimproved heat exchange system for thermo-electric generators, overcomingthe deficiencies of the known devices.

' It is another object of the present invention to provide a novelstructure with regard to the heat exchange device employed in Peltierheating-cooling systems.

It is'a feature of the present invention to provide a uniform tubularconduit upon which is mounted one or more thenno-couples, the effectivejunctions thereof having a member protruding into the conduit, but eachmember being electrically insulated from the others. These members arethus positioned across the path of the common cooling medium passingthrough the conduit which may be a rigid pipe or a flexible hose.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as theinvention, it is believed that the invention, the objects and feature ofthe invention and further objects, features and advantages thereof willbe better understood from the following description taken in connectionwith the accompanying drawing in which:

FIGURE 1 illustrates a cross-sectional view of a heat exchange systememploying the principles of the present invention,

FIGURE 2 is a sectional view of the device shown in FIG. 1 taken in theplane marked II-II therein,

FIGURE 3 illustrates in a cross-sectional view another embodiment of thepresent invention,

FIGURE 4 illustrates a section taken along IV-IV in FIG. 3, and

FIGURE 5 is a cross-sectional view of a simplification of the deviceshown in FIGS. 3 and 4.

Turning now to the detailed description of the drawings, in FIGS. 1 and2 there is first shown a chute, pipe or tubular conduit 1 made of anelectrically insulating material and being passed through by a coolingmedium in a direction positioned in the plane of the drawing in FIG. 1and perpendicular thereto in FIG. 2.

There is a slot shaped opening in pipe 1 and a metallic tongue 2 passestherethrough so as to be positioned in and across the path of thecooling medium. Tongue 2 is a member of the heat exchanger 3 andpreferably is integral therewith. Thus, there is a good heat conductiverelationship present as between tongue 2 and the main part of heatexchanger 3. There are provided two thermo-couple members 4 and 5 ofdiiferent types of thermo-conductivity. Heat exchangers 6 and 7 aresecured to elements 4 and 5, respectively. Elements 3 to '7 togetherform a thermo-couple, as the primary element of a thermo-electricgenerator.

Heat exchangers 6 and 7 are provided with aligned bores 8 and 9,respectively, used for input or output of heat. Elements 6 and 7 alsoserve as electrical contact terminals for the electric current fedthereto, and the heat exchanger 3 defines the effective junction ofmembers 4 and 5.

Tongue 2 is provided with an insulating layer, 2' such as a lacquer orthe like, electrically insulating tongue 2 completely from the coolingmedium passing through pipe 1. This is an important feature if pipe 1 isprovided with a plurality of electrically interconnected thermocoupleelements as described, each one operating at a different level ofelectrical potential.

The overall electrical resistance of the thermo-couples used asPoitier-coolers or heaters is very low indeed, even including alladditional electrical conductors employed. Thus, a leakage path throughthe cooling medium might not be a serious deficiency. Nevertheless, incase the number of thermo-elements employed is large, such leakage ofcurrent might reduce the efiiciency of the cooling system to an extentwhich cannot be neglected. The insulating layer 2 is to prevent thisleakage current, and it covers completely the surface of member 2protruding into pipe 1.

It was said above that there is a voltage present between neighborhoringthermo-couple junctions influenced by the cooling medium; but thisvoltage is a small one. Thus, the layer 2 needs to be only very thin,but of course, thick enough to prevent any break-through. This feature,in turn, is of advantage because layer 2' must not impede the heatexchange between tongue 2 and the cooling medium in pipe 1. In addition,of course, one will select the layer 2' of a material of good heatconductivity.

The device as shown can operate as a Peltier cooler as well as a heater;the respective mode of operation depends upon the direction of theelectric current through the thermo-couple, and whether junction 3 is ahot junction or a cold junction. The flow of heat between the medium andthe various tongues such as 2 will then have a direction accordingly.

It is not essential, that the pipe 1 be completely made of anelectrically insulating material. It can be made of a conductivematerial, but then a layer of insulating material must be interposedbetween such pipe and elements 2 and 3.

The invention is susceptible of embodiments in which the heatexchangemember protruding into the pipe serves also as a securing frame or as asupporting structure of the pipe and the heat exchanger as a whole. Itis possible to provide structure so that the heat exchanger togetherwith the thermo-couple or couples supports the pipe or vice versa. Thefollowing figures illustrate such features.

In FIGS. 3 and 4 there is shown a rubber or a tombac hose 10 having apair of openings 11 and 11', the opening of each pair being aligned andhaving a common axis disposed transversely to the center axis of' thehose; the pairs of openings are disposed along the latter axis.

o Each-pair receives a cylindircal heat exchanger 30, thus extendingalso transversely with respect to the axis of hose 10. Each heatexchanger has a threaded bore receiving a screw 13 fastening the heatexchanger to the hose whereby a washer 14 is disposed between the headof screw 13 and hose 1! for sealing the interior thereof from theoutside. A ring 15 receives heat exchanger 30 and serves as a spacerbetween opposing walls of hose 10 so as to prevent any squeezingthereof. There are provided circumferentially disposed and radiallydirected bores in ring 15 permitting passage of a cooling medium asclose as feasible to heat exchanger 30.

A heat exchanger and conductor plate 12 connects heat and anelectrically conductive member 12' to member 30. Each thermo-couple iscompleted by thermo active members 16 and 17 as well as outer heatexchangers 13 and 19 having bores for passage of an outer heat exchangeor cooling medium. Plate member 12' defines the effective junction beingin heat exchange with the medium passing through hose 10. There may beprovided another washer, disposed between hose 10 and plate 12.

As stated above, the several therrno-elements such as the two shown inFIG. 3 are disposed so as to be positioned in parallel to the axis ofhose it). This is not an essential feature and other configurations arepossible. For example, the thermo-elements can be disposed along ahelical line around hose 19. In this instance FIG. 3 is to be understoodto illustrate a section where the section plane illustrated at left handportion and the section plane of the right hand portion do not coincidebut are azimuthally displaced with respect to the axis of hose It). Thedevice shown in FIG. 3 and FIG. 4 can be understood that the hose llt)rests on the plates 12, or that the thermo-cOuples are supportedthereon.

A simplification of the mutual supporting structure of hose and heatexchanger as shown in FIGS. 3 and 4, is shown in FIG. 5.

A hose 24 is assumed to have sufiicient rigidity so as to providesufiicient sealing and supporting structure without washers and spacerssuch as shown in the preceding figures.

A heat exchanger 21 is provided with an extension identified as member2%} having two grooves 22 and 23 receiving the walls of aligned bores inhose 24. This combines sealing and spacing. The thermo-couple members 23are connected to plate 21 so as to form a thermocouple similar to theone shown in FIGS. 1 and 2. In this embodiment, the hose 24 will retainits circular cross-section.

It will be observed, that the heat exchange between the elementsprotruding into the pipe or hose as shown in the various examples can beimproved, if such elements are provided with additional tongues, fins,etc. increasing the active or available surface for interaction with thecooling medium. This is also shown by way of example in FIG 5,illustrating disks 25 and 26 mounted on member 24 and offering extendedheat exchange surfaces in the direction of fiow of the cooling medium(arrow 27). The invention is not limited to the embodiments describedabove but all changes and modifications thereof not constitutingdepartments from the spirit and scope of the invention are intended tobe covered by the following claims.

We claim:

1. Thermo-electric device operating with the Peltier effect comprising:a tubular element for a heat exchange medium passing therethrough andhaving at least one aperture the walls of which are electricallyinsulating; at least one thermo-couple disposed outside of said tubularelement and including means defining a thermo-couple junction beingdisposed also outside of said tubular element; and a heat exchangemember electrically and heat conductively connected to said meansdefining said junction and protruding through said aperture into theinterior of said tubular element while extending substantially acrossthe axis thereof.

2. Thermo-electric device operating with the Peltier effect comprising:a tubular element made of electrically insulating material for passageof a heat exchange medium passing therethrough; thermo-couple members ofdissimilar thermo-electric conductivity disposed outside of said tubularelement; connecting means secured to said members so as to form athermo-couple junction disposed also outside of said tubular element;and a heat exchange member electrically and heat conductively connectedto said connecting means and protruding into the interior of saidtubular element and extending substantially across the center axisthereof.

3. Thermo-electric device operating with the Peltier effect comprising:a tubular element for a heat exchange medium passing therethrough andhaving at least one aperture the walls of which are electricallyinsulating; at least one therrno-couple disposed outside of said tubularelement and including means defining a thermo couple junction being alsooutside of said tubular element; and a heat exchange member electricallyand heat conductively connected to said means defining said junction andprotruding through said aperture into the interior of said tubularelement substantially across the axis thereof, said member being coveredwith a layer of electrically insulating but thermally conductivematerial.

4. Thermo-electric device operating with the Peltier effect comprising:a flexible hose made of electrically insulating material for passage ofa heat exchange medium therethrough; a thermo-couple disposed outside ofsaid flexible hose and including a therrno-couple junction being alsodisposed outside of said flexible hose; and a heat exchange memberelectrically and heat conductively connected to said junction andprotruding into the interior of said flexible hose substantially acrossthe axis thereof.

5. Thermo-electric device operating with the Peltier effect comprising:a rubber hose for passage of a heat exchange medium therethrough; athermo-couple disposed outside of said rubber hose; and a heat exchangemember electrically and heat conductively connected to said junction andprotruding into the interior of said rubber hose substantially acrossthe axis thereof.

6. Thermo-electric device operating with the Peltier efiect comprising:a tubular element for a heat exchange medium passing therethrough andhaving at least one aperture the walls of which are electricallyinsulating; at least one thermo-couple being disposed outside of saidtubular element and having a thermo-couple junction being disposed alsooutside of said tubular element; and a heat exchange member electricallyand heat conductively connected to said junction and protruding throughsaid aperture into the interior of said tubular element substantiallyacross the axis thereof, said heat exchange member providing securingstructure of mutual support of said tubular element and saidthermo-couples.

7. Thermo-electric device operating with the Peltier effect comprising:a tubular element for a heat exchange medium passing therethrough andincluding electrically insulating means defining two openings alignedtransversely with respect to its center axis; a thermo-couple having ajunction disposed outside of said tubular element adjacent one of saidopenings; and a heat exchange member electrically and heat conductivelyconnected to said junction and having two grooves snugly receiving theelectrically insulating Walls of said openings, respectively.

8. Thermo-electric device operating with the Peltier effect comprising:a tubular element for a heat exchange medium passing therethrough andincluding electrically insulating means defining two openings alignedtransversely to the axis of the tubular element; a thermocouple having ajunction being disposed outside of said tubular element adjacent one ofsaid openings; a heat exchange member passing through said opening andbeing electrically and heat conductively connected on one end with saidjunction; and a screw for tightening the other end of said member to theadjacent portion of said tubular element.

9. Device as set forth in claim 8, including at least one Washer forsealing at least one of said openings With respect to the portion ofsaid member passing through.

10. Therrno-electric device operating with the Peltier eifectcomprising: a tubular element for a heat exchange medium passingtherethrough; a plurality of thermocouples disposed outside of and alongsaid tubular element, each thermo-couple having a therrno-couplejunction; and heat exchange members electrically and heat conductivelyconnected to said junctions of the same type of the severalthermo-couples said tubular element including protruding into theinterior of said tubular element; and insulating means for electricallyinsulating said members from each other.

11. Device as set forth in claim said plurality of thermo-couples beingdisposed along said tubular element in axis-parallel relationshiptherewith.

12. Device as set forth in claim 10 said plurality of thermo-couplesbeing disposed along a helical line on said tubular element.

13. Device as set forth in claim 1, said member including means forenlarging its surface in the direction of flow of said medium.

14. Device as set forth in claim 4, said hose being made of tombac.

l5. Therrno-electric device operating With the Peltier effectcomprising: a flexible electrically insulating hose being passed throughby a heat exchange medium and having tWo openings aligned transverselywith respect to the outer axis of the hose; a thermo-couple having ajunction disposed outside of said hose including a supporting platebeing disposed directly secured in electrical and heat conductiverelationship to said plate and passing through said tWo openings securedto said plate and passing through said two openings so as to extendtransversely to the flow of said medium; and means for sealing saidopenings.

References (hired in the file of this patent UNITED STATES PATENTS

1. THERMO-ELECTRIC DEVICE OPERATING WITH THE PELTIER EFFECT COMPRISING:A TUBULAR ELEMENT FOR A HEAT EXCHANGE MEDIUM PASSING THEREGTHROUGH ANDHAVING AT LEAST ONE APERTURE THE WALLS OF WHICH ARE ELECTRICALLYINSULATING; AT LEAST ONE THERMO-COUPLE DISPOSED OUTSIDE OF SAID TUBULARELEMENT AND INCLUDING MEANS DEFINING A THERMO-COUPLE JUNCTION BEINGDISPOSED ALSO OUTSIDE OF SAID TUBULAR ELEMENT; AND A HEAT EXCHANGEMEMBER ELECTRICALLY AND HEAT CONDUCTIVELY CONNECTED TO SAID MEANSDEFINING SAID JUNCTION AND PROTRUDING THROUGH SAID APERTURE INTO THEINTERIOR OF SAID TUBULAR ELEMENT WHILE EXTENDING SUBSTANTIALLY ACROSSTHE AXIS THEREOF.